1. Field of the Invention
The present invention relates to a four-way valve for use in a regenerative thermal oxidizer (RTO) assembly and other regenerative heat exchange devices.
2. Description of the Prior Art
RTOs are used in a number of industries to reduce the quantity of contaminants in a contaminated gas. In an RTO, the contaminated gas is routed through a flow path, which includes a combustion chamber for oxidizing the contaminated gas to produce a clean gas. A first recovery chamber is disposed in the flow path on one side of the combustion chamber, and a second recovery chamber is disposed in the flow path on the other side of the combustion chamber. Each of the recovery chambers typically includes a ceramic media. The RTO alternates between a first cycle with the gas flowing in a first direction and a second cycle with the gas flowing in a second direction. While operating in the first cycle, as the high temperature clean gas leaves the combustion chamber, it is routed through the first recovery chamber. In the recovery chamber, heat is transferred from the clean gas to the ceramic media. The flow of the gas is reversed during the second cycle such that the contaminated gas flows through the heated first recovery chamber before entering the combustion chamber. Heat is transferred from the hot ceramic media to the contaminated gas, and consequently, less energy is required to oxidize the contaminated gas in the combustion chamber.
A valve assembly is required to direct the gas in the first direction through the flow path while operating in the first cycle and to direct the gas in a second direction through the flow path while operating in the second cycle. One such valve assembly is shown in FIG. 3 of U.S. Pat. No. 5,515,909, issued to Tanaka on May 14, 1996 (hereinafter referred to as Tanaka '909). Tanaka '909 shows a four-way valve assembly including a housing presenting an open interior and having a front, a back, an input side, and an output side. The input side of the housing defines an intake, and the output side of the housing defines an outlet. A partition is disposed in the open interior to divide the interior into an input zone and an output zone. The housing defines an input aperture and an output aperture. A pivot shaft rotatable about an axis is disposed in the interior of the housing, and a pair of opposing dampers engage the pivot shaft and extend radially outwardly therefrom for rotating with the pivot shaft to restrict the flow of gas through the apertures during the first and second cycles.